Lesions and Diseases of the Spinal Cord: Brown-Séquard Syndrome and Tabes Dorsalis

00:00 Welcome to this lecture on the spinal cord.

00:06 Our first slide depicts a lesion of the spinal cord.

00:10 This lesion is involving the dorsal columns/medial lemniscal system.

00:18 The lesion at this level within the spinal cord is affecting the first order neurons as they ascend and this lesion then is ipsilateral and as a result to this lesion being on the ipsilateral side of the pathway, there will be an ipsilateral loss of function below this level of the lesion.

00:41 The loss of function would involve the loss of fine touch, two-point discrimination, loss of pressure and vibration senses, as well as conscious proprioception as these are the normal functions that are conveyed by this ascending pathway.

01:02 Here, you’re looking at a cross-section through the spinal cord.

01:07 And the lesion is depicted over here in the shaded light green area.

01:13 And so if we identify the lesion and the accompanying clinical features, the lesion that’s a hemisection of the spinal cord as you see here is referred to as Brown-Séquard Syndrome.

01:27 Brown-Séquard Syndrome is gonna involve various aspects of the spinal cord, the dorsal columns would be involved in through here.

01:38 So again, this will be ipsilateral loss of fine structure, two-point discrimination, vibration, pressure, and conscious proprioception at and below that particular level of the lesion.

01:54 The spinothalamic tracts are also involved here and in this case, there will be a contralateral loss of pain and temperature 1-2 segments below the lesion, and the reason that the loss of pain and temperature is 1-2 segments below the lesion is due to Lissauer’s tract.

02:22 Lissauer’s tract, when the neurons, or at this level are ascending a couple of levels, and so this is involving those levels that are below this particular level in the spinal cord.

02:36 Please note specifically that at level of the lesion, there is complete ipsilateral loss of all sensations.

02:45 Lastly, the corticospinal tracts are involved.

02:51 and at this particular level, there will be an ipsilateral paresis at and below the lesion.

03:00 Here, we’re looking at a continuation of Brown-Séquard Syndrome.

03:07 In addition, to what we saw in the previous slide, descending hypothalamics will be lesioned.

03:15 And so we lose the descending hypothalamic output.

03:18 And at this lesion is above spinal cord level T1.

03:23 The loss of sympathetics will result in ipsilateral Horner’s Syndrome.

03:29 So, miosis, anhidrosis, and ptosis would be the triad of symptoms associated classically with Horner’s Syndrome.

03:42 Lower motor neurons would be involved here.

03:47 They would be damaged in the dorsal grey horn area and as a result there will be flaccid paralysis at the level of the lesion.

04:00 And as it’s shown here, with paralysis, loss of muscle tone, and just a general state of hypotonia.

04:09 Here, we’re looking at again a cross-section of the spinal cord but this is a different lesion, or have a different set of clinical features.

04:25 Here, the lesion is, in this area of the cord, the posterior part.

04:30 So it’s involving the dorsal columns.

04:35 This particular lesion is referred to as Tabes Dorsalis.

04:42 And this disease is characterized by a slow degeneration, demyelination of nerves found primarily in these dorsal columns.

04:53 So, you have the fasciculus gracilis and the fasciculus cuneatus ascending through this area of the spinal cord.

05:03 What are the accompanying clinical features of tabes dorsalis? Individuals that have this lesion complain of intense pain.

05:17 They complain of disturbed sensation.

05:23 and then usual high step gait.

05:30 There gait it is unsteady and they will exhibit a positive Romberg’s sign, which is demonstrated by a loss of balance when the patient has their eyes closed.

05:50 And this will be due to a loss of proprioception.

05:55 Due to disruption of proprioception, patients also exhibit sensory ataxia.

06:02 Sensory ataxia is characterized by an unsteady, stomping gait.

06:07 This is exaggerated when the eyes are closed.